fix: force immediate redraw after font switch in applyFont()

Without _next_refresh = 0 the Settings screen would continue using its
2-second refresh interval after a font change, showing stale rendering
for up to 2 seconds. Mirrors the pattern used by setBrightnessLevel().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/ui-new/UITask.cpp

@@ -1561,6 +1561,7 @@ void UITask::applyBrightness() {
 void UITask::applyFont() {
   if (_display != NULL && _node_prefs != NULL) {
     _display->setLemonFont(_node_prefs->use_lemon_font != 0);
+    _next_refresh = 0;
   }
 }